Part 8. Factory floored – (or what an average Joe notices when working with an ex-works spannerman)

Let’s be clear, I’m not a great mechanic. In spite of a couple of race wins in 1993 on an FZR600 that sounded like a typewriter after my interpretation of the right shims had capped off the build, I’ve never fathered powerplants that were coveted for their enduring success. My engine building style if called anything at all, would be called a triumph of wishful thinking (and frugality) over talent.

Paul Boulton. Factory trained, really.
Paul Boulton. Factory trained, really.

So, roll forward 20 odd years and let the education commence.

I’ve taken several pilgrimages to the Fens since the Autumn to work on the Kat engine with Paul Boulton ( Learning from a bloke that was already a better mechanic than I’ll ever be before he worked for various Suzuki factory teams during the 80’s, is a little daunting. But, here’s the good bit; I came to realise great engine building may not solely be the preserve of factory trained spanner Gods, it’s there for us all. Really.

I could have written up a long list of the things we did to build this engine, all 72 stages of them, but that wouldn’t itself reveal what it is that most impressed me about working with our tame factory fettler. So, what follows are the things I saw Paul do, that made me realise it’s not impossible to potentially make a good job for any of us!

Where does our Factory genius start?

1) Cleanliness

Oh, this is obvious right? Well, yes, it is. But there are degrees of cleanliness, and having watched and partaken in motocatman levels of cleanliness, I think I’ve recalibrated somewhere well North of what I previously thought “workable”

Engine parts, tools and workspace – all clean, tidy and organised. An uncluttered environment is as important as a clean one. Make loads of space, much more than you think you need. Having space to put things as you work is a joy, it changes the whole feeling of working on a difficult project.


I wouldn’t have used a pressure washer to wash our soda-blasted crankcases. I’d have reached for the brake cleaner or GT85 and a rag if left to my own devices. The tell-tale that a proper wash out had been needed, were the crystallised streaks of soda which appeared during drying from deep stud holes and oil ways. I’d definitely have left soda medium inside the important bits doing it my way. Soda is not a nasty abrasive medium, but as Suzuki didn’t design the engine to run with soda inside it, it’s got to go.


Parts that are greasy or oily get cleaned with a brush in thinners or petrol, fasteners that display corrosion get treated to the wire wheel on the bench grinder. Nothing, and I mean nothing, gets to the engine without going through this process. If you dropped any part of this engine in your tomato soup, you’d not think twice about licking it off once you’d retrieved it.

Before and after the wire wheel, every fastener got the treatment.

Lesson learnt. Be thorough when cleansing, if necessary, use force, chemicals, or both!

2) Preparation

Paul’s own opening salvo in the battle of the build was to remove sharp edges from the mating surfaces of the crankcases. A small hand tool he has is chased around the edges and takes off tiny amounts of material, leaving them with a “hand-friendly” finish.

Think crankcase mating surfaces that have spent their entire life bolted together are perfectly flat? Running an oilstone over a crankcase and seeing any kind of “witness” mark, where the stone is removing material, means you’ve just found something that is at least a thousandth of an inch out of true. Around several of the lower crankcase stud holes, we saw just this happen.


A shining doughnut of fresh metal appears as the oilstone traces over stud holes that have lifted. The studs pull the crankcase into a shallow volcano shape as they are torqued up. Well I never.


Every thread was treated to the same care programme; a countersinking hand tool was run in the neck of the thread to chamfer the entry for the stud or bolt. A further quick clean with the oilstone removes any detritus from this process.

Chamfering the freshly rebored liners to make the rings journey home a little smoother.
Chamfering the freshly rebored liners to make the rings journey home a little smoother.

Then using a drill and a tap, every thread was rapidly addressed so it would prove the perfect host for it’s partner fixing. I’d have turned my engine to scrap or at least in need of 36 timeserts if I’d tried the same thing at the same pace! Which leads nicely to the next thing worthy of note…

3) Fast through the fast, slow through the slow.

It’s not just Guy Martin that thinks this is a good approach.

Watching Paul run rapidly through the many crankcase threads with a tap inserted into a power drill made me tense. I’m not fluent in tap, all I know is they can damage stuff in a heartbeat, and that I wouldn’t trust myself with one on stuff I don’t want wrecked. So the speed and precision with which the threads were cleaned out was shocking and joyous all at once.

But then comes the need to calm it down. We’re not rushing anything, we’re taking the right amount of time to do the job properly. Take our camshaft issue.

The cams in the GSX aren’t unusual, they run on plain aluminium journals that split in half and bolt together. Paul’s first bolt up of the cams was done into a bare head (no valves, springs or followers) without the addition of even a single drop of oil. Unusual. Every other moving part or union we’d built thus far, sensibly had a little oil added to it.

So why leave the cams dry and insert them into a bare head? Well, once the caps had been torqued down, Paul gives the cams a simple test; do they turn?

Ours didn’t. They felt like an unmoving part of the cylinder head. Oh.

The bearing scraper came out (another tool I felt I couldn’t be allowed near) This next bit took somewhere around 3 hours. Remove tiny, tiny amounts of aluminium where the cam/journal union shows signs of fouling, re-torque the caps, then test resistance again. Repeat. In all, this was repeated 5, maybe 6 times.


The result? Cams that spin freely with the tiniest input from a fingertip. The total amount of material removed to facilitate that? I doubt if it would tip the scales against half the head of a match. Welcome to the Factory difference. Oh yeah.

If it needs time, take it. If doesn’t, then don’t.

4) Saving weight

He’s obsessed with saving weight. Utterly obsessed. He loves titanium fasteners, he loves holes already made in things, he loves drilling things that came without holes, he loves removing material, he hates things made from Steel that could be made of Titanium, Magnesium or Aluminium (which on a Katana, is almost everything!)

His lust for lightness first reared it’s head when he was running the edge chamfering tool around the mating halves of the crankcases (see point 2 above). The infinitesimally small little curls of aluminium that he took off seemed disproportionately pleasing; “It’s all saving weight” he remarked. I chuckled back, thinking he was joking. He wasn’t. He didn’t even understand why I thought he was joking. He’s really serious about saving weight!

If you ever get the chance to buy him a beer and kick back for an hour (please do, he’s a lovely bloke), ask him about factory mechanics and the quest to save weight. You’ll listen, as did I, to joyously delivered tales of factory spannermen drilling the outside of crankcases to make dozens of small countersunk dimples, or the brilliance of titanium factory bolts that came with drillings all the way through the middle and have concave domes and drillings in the head. He loves all that, really loves it!

Drilling = saving weight = smile. Simple.
Drilling = saving weight = smile. Simple.

Of course he’s not wrong. If you’re fighting for the big prizes, World titles, why on earth would you carry even a gram of weight around that you don’t need? I tried a couple of times to break it to him that the big prizes aren’t where we’re at with this bike, and the most significant weight savings I’ll make at Spa will probably be by reducing the size of Pizza I have the night before from 15 to 12 inches, but it seemed cruel to carry it through. He doesn’t want to be mediocre, he’s in the competition already.

5) Concentrate

I have spent dozens of hours in the workshop with Paul during this build, and I can’t recall him ever dropping anything we were doing to take a call whilst we worked on this engine. I know he’s not unpopular, and I know he has a phone, it’s just that calls have never been allowed to interfere with the job in hand. I like that.

We’re all slaves to the permanently connected world these days, and how can a call in the middle of a job that needs all your brain on it be in any way helpful? Such a basic tip to share, but why not allocate all available attention to the task in hand. Turn the phone off.

The phone might be off, but the space heater is on, and warming the crankcases ready for a bearing to slot home with ease.
The phone might be off, but the space heater is on, and warming the crankcases ready for a bearing to slot home with ease.

6) Take a break.

Try getting Motocatman to not stop at lunchtime. Good luck with that.

We did some long hours on most days we worked together, but we always stopped for food and a brew at good times. Hungry people are tired and grumpy people, and tired and grumpy people probably don’t build engines as well as satisfied well-fed ones.

7) Don’t get pissed off.

Try NOT swearing at your engine. I thought Paul was being polite to start with, but he consistently under-swears at times I thought wholly appropriate. When the going gets tough, just throwing your hands up, cursing and wishing it was different with colourful language isn’t part of his process at all.

When (it’s not an “if”) something goes awry on a build, accept it, think about all the possible ways around it, pick one, positively start over. Cool.

Taking a level mood and a cool head into the workshop is really going to help. In fact, it’s not a bad way to live your life either. How profound.


So, in conclusion, whilst there’s abundant experience and confidence in everything Paul does, only a lucky few will ever get to experience even a fraction of the journey that made that happen for him.

But making the engine go together in such a lovely way isn’t conditional to years of Factory experience, instead we (presuming we’re the average home mechanics of the world) could probably get by with a methodical, level headed and sensible approach, conducted in a nice environment with space, cleanliness, good reference materials and no distractions.

Simple huh? I guess my next engine build will prove if it really is!


Paul Boultons own Top 3 Tips for great engine building

1. Cleanliness – be clean, be tidy, be methodical. (we’ve already covered most of that)

2. Use and create good references as much as possible. You can’t remember everything, so check torque settings in the manual. Check anything you’re unsure of – it’s not a crime to check anything or everything. Get it right first time. Also make records as you go – taking pictures of the engine before it’s apart, whilst it’s coming apart and after it’s apart can save you a hell of a lot of head scratching later.

3. If you’re going to ignore the factory settings and recommendations during a build, you’d better have a very good reason to do so. Third hand conjecture from an internet forum does not count as a very good reason! Case in point – Paul uses the original mineral oil spec of 10W/40 in the early 80’s 4 strokes he builds, because that’s what they were built to run. Arguably there’s better oil available nowadays, but these engines weren’t designed for it. Why create your own new problems?